The present invention relates to a multi-layer water soluble or dispersible packaging film and its use in packages for containing potentially hazardous organic chemicals. More particularly, the present invention relates to a water soluble or dispersible packaging system having a continuous film barrier on the interior portion of the package for containing agricultural chemicals having a tendency to adversely affect or otherwise be deleterious to the outer film portion of the water soluble or dispersible packaging system.
Pesticides, such as herbicides, insecticides, fungicides and other types of agricultural chemicals (referred to herein as xe2x80x9cagrichemicalsxe2x80x9d) are often potentially harmful materials and are commonly made in concentrated form which can be as a solid, a liquid, a dispersion or a gel, for example. Such materials typically need to be diluted with water prior to use. Numerous other types of hazardous and toxic materials are also commonly sold and used on a commercial basis. Containers are needed for the aforementioned types of hazardous and toxic materials in order to conveniently distribute, sell and utilize such materials.
Typically, such containers are metal or blow molded plastic. However, there are hazards and difficulties in handling, storing and using such types of containers and materials. In addition, particularly with highly concentrated materials, hazards exist when such concentrates are diluted for use, such as when pouring the concentrate into a tank or other container. For example, the concentrated material can splash or spill in unintended locations, causing unintended human, animal or other contact with the concentrate.
In addition, disposal of the metal or plastic containers can be a problem since some residual concentrated material will remain in the original container. Thus, disposal of such containers can become an environmental problem.
It is known to package certain materials, including certain liquids in water soluble bags consisting of a layer of cold water soluble polyvinyl alcohol. Such packaging is disclosed in U.S. Pat. No. 5,351,831, for example. However, such packaging and similar types of packaging are not suitable for containing agrichemicals that deleteriously affect cold water soluble polyvinyl alcohol film, such as by chemical or physical reaction with it, including dissolving the cold water soluble film. Consequently, a need exists for a suitable cold water soluble or dispersible container that can contain agrichemicals and other materials that chemically, physically or otherwise deleteriously react with the water soluble film that forms the water soluble bag. In addition, a need exists for a cold water soluble or dispersible bag for storing such agrichemicals and other materials that is reliable and easy to produce.
In accordance with the present invention, a multi-layer cold water soluble or dispersible packaging film is provided which comprises: (i) a first xe2x80x9couterxe2x80x9d continuous cold water soluble or dispersible film layer of sufficient thickness and strength for use as a package to contain chemicals, and (ii) a second xe2x80x9cinnerxe2x80x9d continuous water soluble or dispersible film layer which is both chemically differentiated from and thinner than said first layer. The multi-layer film of the present invention is suitable for use as a package to contain potentially hazardous materials, particularly chemicals that dissolve water soluble film or chemically, physically or otherwise deleteriously react with or adversely affect water soluble film. The water soluble or dispersible packaging system prepared from the multi-layer film generally is conveniently in the form of a bag, a pouch or a sachet. Other conventional container configurations also are contemplated by the packaging system of the invention.
As used herein, the term xe2x80x9cchemicalxe2x80x9d includes all types of potentially hazardous chemical materials, particularly organic chemicals including, but not limited to, agrichemicals. The term xe2x80x9cagrichemicalsxe2x80x9d includes, for example, agronomically useful chemicals from the following classes: plant nutrients, plant growth regulators, plant protection agents such as pesticides (e.g., herbicides, insecticides, nematocides, acaricides, molluscicides, fungicides, etc.), activity promoters, penetrating agents, synergists, antidotes and safeners, activators, compatibility agents, and adjuvants. The term xe2x80x9cagrichemicalsxe2x80x9d also includes agrichemical compositions (mixtures of one or more agrichemicals with any conventional agronomically acceptable carrier or diluent). The multi-layer film of the present invention can be used to make water soluble or dispersible packages that are suitable for containing chemicals such as agrichemicals or agrichemical compositions in the form of liquids, solids, or gels. Suitable liquids are, for example, in the form of dispersions, solutions, suspensions, emulsions and colloids. Solids are in the form of powders, granules and prills, for example. The term xe2x80x9ccold waterxe2x80x9d means liquid water at a temperature of less than 50xc2x0 C., preferably lower than 35xc2x0 C., for example, between 5xc2x0 C. and 35xc2x0 C. xe2x80x9cCold water solublexe2x80x9d means completely soluble in cold water. xe2x80x9cDispersiblexe2x80x9d means disintegration or dissipation as fine particles. Preferably, the dispersed particles are small enough to pass through the orifice of a conventional agrichemical spray apparatus or are filterable without plugging the spray orifice or filter of a conventional agrichemical sprayer. For example, particles having a mean particle size of from about 0.1 to about 250 microns as measured by the CIPAC MT176 test for dissolution capacity of water soluble sachets are considered to be dispersible for the purpose of the present invention. The term xe2x80x9csubstantially adversely affectxe2x80x9d in the context of contact with cold water soluble film by an agrichemical material or other chemical material means that the material is not suitable for containment in a package made of the film because of any deleterious effect caused by contact of the material and the film, whether a chemical or physical reaction including, for example, dissolving the film by the material and unwanted physical leaching of film components into the material. In addition, the material stored in the package can affect the film material by, for example, physically altering the properties of the film such as extraction of plasticizer which makes the film brittle, making the film insoluble or otherwise unsuitable for use in packaging agrichemicals.
The multi-layer cold water soluble or dispersible film in accordance with one aspect of the invention includes a first outer continuous layer of cold water soluble film of sufficient thickness and strength to provide sufficient structural strength for use as a bag to contain liquid. Advantageously, the first or outer film layer may itself contain multiple layers of the same film type (such as co-extruded or tri-extruded cold water soluble films) as is known in the art. The multi-layer cold water soluble or dispersible film of the invention includes a second inner layer, chemically differentiated from the outer layer, which is an inner continuous or substantially continuous barrier layer of a material that can be cold water or hot water soluble or insoluble film securely adhered to and in intimate contact with the outer layer. The inner barrier film layer serves the purpose of preventing, impeding or otherwise reducing the interaction between the contents of a package made from the multi-layer film and the first outer film layer. In one embodiment, the inner barrier film layer is substantially continuous with the outer film layer such that the multi-layer film has edge or border areas which do not contain a barrier film layer to facilitate heat sealing or other sealing means.
When water insoluble or hot but not cold water soluble material is the barrier, the inner continuous layer of water insoluble film is frangible or otherwise lacks sufficient structural integrity to contain the chemical in a bag. Typically, the thickness of the first outer cold water soluble layer is much thicker than the second inner barrier layer. In one embodiment, the thickness ratio of the first outer layer to the second inner layer is from about 500:1 to about 2:1, preferably from about 400:1 to about 3:1. When a bag formed of the inventive multi-layer water soluble film is sealed with the chemical contained therein, once the water soluble film layer is dissolved, such as when the package is placed in water, the inner continuous barrier layer releases the chemical in the bag by dissolving or dispersing. This occurs because the outer water soluble structural layer has dissolved and the barrier or inner water insoluble layer is frangible or otherwise lacks sufficient structural integrity to remain intact and contain the agrichemical particularly when agitated in the spray tank of a conventional agrichemical sprayer. Preferably, as noted above, the barrier layer disperses or dissolves sufficiently to allow flushing into sanitation systems, passage through filters and spray nozzles.
Suitable materials for the first cold water soluble or dispersible film layer can be selected from a wide variety of materials including, for example, polyvinyl alcohol, polyoxyethylene or a combination thereof.
The second barrier film layer can be cold water soluble, hot water soluble or dispersible. In order to properly function as a barrier, the barrier material should be at least not as susceptible to interaction with the agrichemical or other material to be packaged as is the outer film layer.
In accordance with another aspect of the present invention, a water soluble or dispersible package (conveniently a bag) is provided that is suitable for containing agrichemicals and other chemicals which substantially adversely affect water soluble film. The bag is also useful for containing other types of chemicals. The water soluble or dispersible bag in accordance with the invention is formed from the aforesaid inventive multi-layer water soluble film. For example, the bag is formed by sealing two sheets of the multi-layer film together at the edge regions by means of an adhesive or heat seal.
In accordance with another aspect of the present invention, a water soluble or dispersible bag is provided for containing agrichemicals, the bag being particularly suitable for containing agrichemicals that substantially adversely affect cold water soluble film. The bag is composed of an outer layer of cold water soluble film and a continuous inner barrier film layer wherein the agrichemical composition does not substantially deleteriously affect the inner barrier film layer and the inner barrier film layer is capable of preventing or impeding the agrichemical composition when stored therein from contacting the outer cold water soluble film layer and wherein when the bag is placed in water with the agrichemical store therein, the water soluble film layer dissolves and the inner barrier layer dissolves or disperses into particles small enough to allow the agrichemical to disperse or dissolve into the water without clogging the spray system.
In accordance with still another aspect of the present invention, a water soluble bag packaging system is provided for containing and transporting chemicals, particularly agrichemicals, which substantially adversely affect cold water soluble film, including by chemical or physical reaction or otherwise. The packaging system includes a bag formed of the inventive multi-layer water soluble film having the inner continuous water insoluble film layer or barrier layer on the interior portion of the bag. The inner barrier layer prevents or impedes the agrichemical composition from contacting the water soluble film layer and when the packaging system is placed in water or other medium that dissolves the water-soluble film layer, the inner barrier layer, lacking sufficient structural integrity and strength to contain the agrichemical contained therein, releases the agrichemical. Consequently, dispersion into the water or other desire medium is provided.
In accordance with still another aspect of the present invention, a method of storing a liquid that chemically, physically or otherwise deleteriously reacts with cold water soluble film in a water soluble film is provided. The method includes forming a bag from a multi-layer water soluble film that is comprised of an outer continuous layer of water soluble film of sufficient thickness and strength to provide adequate structural strength and integrity for use as a bag to contain liquid and wherein the multi-layer water soluble film includes an inner continuous layer of a water insoluble film or water soluble film over the outer layer that is not dissolved by or otherwise is not substantially adversely affected by the chemical stored in the bag. The inner continuous layer lacks sufficient structural integrity to contain the liquid in the bag once the water soluble film layer is dissolved. The method further includes placing the liquid in the bag and thereafter sealing the bag with the liquid contained therein.